1) Field of the Invention
The invention relates to a wafer-type tumbler cylinder, a cylindrical shaft, the indentations, fixing slots and riveting plates of which are made in a consistent integrated operation, thereby facilitating the placement of first and second wafers and springs in the indentations and, furthermore, one spring serves as a shared spring for every pair of first and second wafers. In addition to reducing the material cost of the spring, one pair of first and second wafers is disposed in each indentation so as to increase the difficulty of prying or unlocking by burglars. The improved structure of riveting plates and shared spring for every pair of first and second wafers enables the key to move forward and backward smoothly, and also enables the users to lock and unlock easily and successfully.
2) Description of the Prior Art
A conventional wafer-type tumbler cylinder, as shown in FIG. 5, mainly comprises a sleeve 1a, a cylinder 2a, some wafers 3a and some springs 4a. The sleeve 1a has a bore 11a extending through it lengthwise; the cylinder 2a has a flange 22 and a drive section 23 at the front and rear ends; the cylinder 2a is a cylindrical shaft 20a with several diametrically rectangular through-holes 24a and, furthermore, at the two sides of each rectangular through-hole 24a is a C-shaped recess 25 and a horizontally oriented U-shaped recess 26 (as shown in FIGS. 6 and 7), for the installation of wafer 3a and spring 4a sets.
Each wafer 3a of the conventional wafer-type tumbler cylinder, in addition to a window 31 in the middle of each wafer body 30, has an opposing spring tab 32 and a locating tab 34; when the wafer 3a is inserted into each rectangular through-hole 24a on the shaft 20a of the cylinder 2a, it is first necessary to install a spring 4a into the C-shaped recess 25 at one side of the rectangular through-hole 24a, following which the wafer 3a is then inserted into the rectangular through-hole 24a; but during the installation, since the wafer body 30 of the wafer 3a has the spring tab 32, its insertion occurs without any resistance along the C-shaped recess 25; however, the locating tab 34, disposed in the other side of the wafer body 30, must similarly undergo insertion through the C-shaped recess 25 along the rectangular through-hole 24a, and, as a result, friction occurs along the interior wall of the rectangular through-hole 24a at the opposite lateral of the C-shaped recess 25, and only after this does the locating tab 34 of the wafer body 30 reach into the horizontally oriented U-shaped recess 26, where it becomes nested onto the bottom of the horizontally oriented U-shaped recess 26 (as indicated in FIGS. 6 and 7), and also only then is the cylinder 2a installed in the bore 11a of the sleeve 1a, which completes the assembly of one wafer-type tumbler mechanism. As such, during the insertion of each wafer 3a into the rectangular through-hole 24a on the shaft 20a, the operation is difficult and adversely affects the production process. After each wafer 3a has been inserted into the rectangular through-hole 24a, the locating tab 34 on the wafer body 30 is nested onto the bottom of the horizontally oriented U-shaped recesses 26; however, the height of the locating tab 34 is quite limited and, furthermore, the locating tab 34 is subjected to the outwardly exerted elastic force of the spring 4a, thus the wafer 3a is often ejected out of the rectangular through-hole 24a. Such situation results in a troublesome and inconvenient assembly operation as the cylinder 2a is inserted into the bore 11a of the sleeve 1a, which likewise adversely affects the production process.
In view of such inconveniences and shortcomings during the process of production and assembly operation for the conventional wafer-type tumbler cylinder, the inventor filed a patent application entitled “Wafer-type tumbler cylinder and key” that has been issued as U.S. Pat. No. 7,530,246 B2 on May 12, 2009. The above-mentioned patent not only provides a cylinder for better placement of wafers and springs, but also provides a cylinder with a corrugated-contour keyway having a structure of one shared spring for every two wafers, thereby preventing theft by means of a metal sheet or other equivalent tool inserted for burglarizing. Even though such patent provides a better invention of wafer-type tumbler cylinder and key and many users have good opinions, the inventor still continues to conduct research and development on wafer-type tumbler cylinder and thus results in this improved wafer-type tumbler cylinder with riveting plates and better cylindrical shaft made in a consistent integrated operation.